Calcium carbonate (CaCO3) is a metal carbonate compound and reacts with hydrochloric acid (HCl) to produce carbon dioxide (CO2), calcium chloride (CaCl2) and water. You can see, carbon dioxide gas is released through the solution.
calcium carbonate and hydrochloric acid reaction
CaCO3 + HCl → CaCl2 + CO2 + H2O
